Attempts to modulate and control amplitude, phase, polarization, and the like, of a transmission wavelength in various electromagnetic wave ranges have been widely performed.
In particular, various methods for using a terahertz wave newly developed in an electromagnetic wave range have been proposed recently. An example of the methods may include a method of using designer surface plasmon resonation generated in a terahertz wave, a method of using metamaterial, a method of controlling amplitude of a terahertz wave based on a method of exciting free electrons in semiconductor, and the like.
However, due to limitation of modulation efficiency and inefficiency of fabrication, a new modulation method has been urgently required.